Probing the superconducting ground state of the rare-earth ternary boride superconductors $R$RuB${}_2$ ($R$ = Lu,Y) using muon-spin rotation and relaxation

Abstract

The superconductivity in the rare-earth transition metal ternary borides $R$RuB${}_2$ (where $R$ = Lu and Y) has been investigated using muon-spin rotation and relaxation. Measurements made in zero-field suggest that time-reversal symmetry is preserved upon entering the superconducting state in both materials; a small difference in depolarization is observed above and below the superconducting transition in both compounds, however this has been attributed to quasistatic magnetic fluctuations. Transverse-field measurements of the flux-line lattice indicate that the superconductivity in both materials is fully gapped, with a conventional s-wave pairing symmetry and BCS-like magnitudes for the zero-temperature gap energies. The electronic properties of the charge carriers in the superconducting state have been calculated, with effective masses $m^{\ast }/m_{\mathrm{e}}=$ $9.8\pm 0.1$ and $15.0\pm 0.1$ in the Lu and Y compounds, respectively, with superconducting carrier densities $n_{\mathrm{s}}=$ ($2.73\pm 0.04$) $\times 10^{28}$ m${}^{-3}$ and ($2.17\pm 0.02$) $\times 10^{28}$ m${}^{-3}$. The materials have been classified according to the Uemura scheme for superconductivity, with values for $T_{\mathrm{c}}/T_{\mathrm{F}}$ of $1/(414\pm 6)$ and $1/(304\pm 3)$, implying that the superconductivity may not be entirely conventional in nature.

8 pages, 8 figures

References in corpus (4)

• Evidence for time-reversal symmetry breaking in the non-centrosymmetric superconductor LaNiC${}_2$
• Non-unitary triplet pairing in the centrosymmetric superconductor LaNiGa${}_2$
• Broken time-reversal symmetry probed by muon spin relaxation in the caged type superconductor Lu${}_5$Rh${}_6$Sn${}_{18}$
• Muon Spin Rotation and the Vortex Lattice in Superconductors

Cited by in corpus (5)

• Unconventional superconducting properties of noncentrosymmetric Re5.5Ta
• Pairing symmetry of an intermediate valence superconductor CeIr3 investigated using muSR measurements
• Probing nodeless superconductivity in LaMSi (M = Ni, Pt) using muon-spin rotation and relaxation
• $R$RuB${}_2$ ($R$=Y, Lu), topological superconductor candidates with hourglass-type Dirac ring
• Superconducting ground state of nonsymmorphic superconducting compound Zr${}_2$Ir